The proposed research is a comprehensive, 36-month, synthetic and biological testing program aimed at the development of novel antiprogestational agents that will interfere with progesterone receptor utilization, and that are orally tenfold more potent that mifepristone and have minimal hormonal and antagonistic activity other than antiprogestational. The proposed research may lead to the development of new derivatives of mifepristone that show significantly improved oral antiprogestational potency with less or without antiglucocorticoid activity, and have better pharmacokinetic and solubility characteristics, thus providing a postcoital emergency therapy as well as a new, highly effective, and safe contraceptive agent.